Electronic device and its operation system

ABSTRACT

An electronic device carried around by the user is desired to be used for a long period. In order to achieve this, a high-capacity battery may be incorporated. Since a high-capacity battery is large, its incorporation in an electronic device increases the weight of the electronic device. An electronic device used while being implanted in the body of the user, provided with an emergency power supply, is provided. In an electronic device provided with a plurality of batteries, a transmitting portion and a receiving portion conduct wireless charging among different batteries, and the battery to be charged or used is selected by a power supply management circuit depending on the circumstances.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One embodiment of the present invention relates to an object, a method,or a manufacturing method. The present invention relates to a process, amachine, manufacture, or a composition of matter. One embodiment of thepresent invention relates to a semiconductor device, a display device, alight-emitting device, a power storage device, a lighting device, anelectronic device, or their manufacturing methods. In particular, oneembodiment of the present invention relates to an electronic device andits operation system.

Note that electronic devices in this specification generally meandevices including secondary batteries; and electro-optical devicesincluding secondary batteries, information terminals including secondarybatteries, and the like are all electronic devices.

2. Description of the Related Art

Electronic devices carried around by the users and electronic devicesworn by the users have been actively developed.

Since electronic devices carried around by the users and electronicdevices worn by the users are powered by batteries, their powerconsumption is reduced as much as possible. Particularly in the casewhere a central processing unit (CPU), which consumes a lot of power forits operation, is included in the electronic device, processing of theCPU greatly affects the power consumption of the electronic device.

A semiconductor device including a high-performance integrated circuit(e.g., a CPU) on a plastic or plastic film substrate, which transmitsand receives electric power or signals wirelessly, is described inPatent Document 1.

REFERENCE Patent Document [Patent Document 1] Japanese Published PatentApplication No. 2006-32927 SUMMARY OF THE INVENTION

An electronic device carried around by the user is desired to be usedfor a long period. In order to achieve this, a high-capacity battery maybe incorporated. Since a high-capacity battery is large in size, itsincorporation in an electronic device increases the weight of theelectronic device. Thus, small-sized, high-capacity batteries that canbe incorporated in portable electronic devices are developed. Note thatin this specification, the expression “incorporated in electronicdevices” refers not only to incorporation of a battery in a manner thatthe battery cannot be detached for replacement, but also toincorporation of a battery in a manner that the battery as a form ofbattery pack or the like can be freely detached.

The detail of the power consumption of an electronic device including aCPU will be described. The power consumption can be roughly classifiedinto power consumed by a CPU, power consumed by systems around the CPU,and power consumed by a plurality of input/output devices and peripheraldevices connected to the inside or outside of the electronic device. Thepower consumed by systems around the CPU includes a loss in a converter,a loss in a wiring pattern, and power consumed by a bus, a controller,and the like.

When an electronic device is reduced in size or thickness, a battery isalso subjected to the limitation. As for a battery, however, decrease involume leads to decrease in capacity. Thus, a circuit, a battery, andthe like are stored in a smaller space.

Furthermore, a battery generates heat by charge and discharge, which maythermally affect the surrounding area.

As an electronic device is reduced in size and a circuit, a battery, andthe like are stored in a smaller space, how to control the powerconsumption and heat generation becomes a problem.

An electronic device having a novel structure, specifically, anelectronic device having a novel structure that can be changed in formin various ways is provided. More specifically, a wearable electronicdevice that is used while being worn on the body and an electronicdevice that is used while being implanted in the body are provided.

Particularly in the case where a battery of an electronic device that isused while being implanted in the body is broken or exhausted for somereason, the user may suffer serious damage.

Therefore, an electronic device carried around by the user, a wearableelectronic device used while being worn on the body of the user, and anelectronic device used while being implanted in the body of the user,each provided with an emergency power supply, are provided.

Note that the descriptions of these objects do not disturb the existenceof other objects. In one embodiment of the present invention, there isno need to achieve all the objects. Other objects will be apparent fromand can be derived from the description of the specification, thedrawings, the claims, and the like.

A battery is provided for each of the components used for an electronicdevice, whereby an electronic device having a plurality of powersupplies is obtained. In the electronic device having a plurality ofpower supplies, an operation system by which only the component to beused is selectively driven is employed, whereby power consumption can bereduced.

In addition, the electronic device includes a power supply managementcircuit (power supply monitoring circuit) for managing the plurality ofpower supplies.

A structure disclosed in this specification is an electronic deviceincluding a central processing unit, a display unit, and a receivingunit. The central processing unit includes a first battery and a firstreceiving portion. The first receiving portion has a function ofwirelessly charging the first battery. The display unit includes asecond battery and a second receiving portion. The second receivingportion has a function of wirelessly charging the second battery. Thereceiving unit includes a third battery and a third receiving portion.The third receiving portion has a function of wirelessly charging thethird battery.

An electronic device may be capable of transmission and reception amonga plurality of batteries. Another structure disclosed in thisspecification is an electronic device including a central processingunit, a display unit, a receiving unit, a transmitting unit, and a powersupply management circuit. The central processing unit includes a firstbattery, a first receiving portion, and a first transmitting portion.The first receiving portion has a function of wirelessly charging thefirst battery. The display unit includes a second battery, a secondreceiving portion, and a second transmitting portion. The secondreceiving portion has a function of wirelessly charging the secondbattery. The receiving unit includes a third battery, a third receivingportion, and a third transmitting portion. The third receiving portionhas a function of wirelessly charging the third battery. The powersupply management circuit has a function of wirelessly charging thesecond battery or the third battery with electric power of the firstbattery via the first transmitting portion.

Note that a circuit is connected to each of the batteries to enablewireless charging. At least secondary batteries are electricallyconnected to respective wireless receiving portions via respectiveregulators.

A regulator is an electronic circuit that keeps an output voltage orcurrent constant. A regulator is classified into two kinds, a linearregulator and a switching regulator, depending on the amount of electricload or the like. A switching regulator is also called a DC-DCconverter.

Furthermore, a transmitting portion that is capable of charging abattery with electric power of another battery may be provided for eachof the batteries. The power supply management circuit that manages theamount of electric power of each battery acquires the data on theremaining amount of electric power of each battery regularly orconstantly, and controls the amount of electric power as appropriate.

Taking an information terminal such as a cell-phone and a smartphonehaving a single power supply for example, when the single power supplyis turned off, all of the functions of the device stop. When the powersupply is on, even a functional circuit that is not in use consumessmall electric power because it is in a standby state. If there is afunctional circuit that is not in use, the electrical connection betweenthe functional circuit not in use and the battery may be off to save thepower consumption. For example, in the case where only a still image isdisplayed on a display portion of an information terminal, theconnection between a CPU and a battery for the CPU is turned off inorder that the CPU not in use is turned off. Then, only a battery for acircuit that is driven to display the still image on the display portionin use is used. In that case, the CPU of this information terminal isnot operating although the still image is displayed, and the powerconsumption of the CPU can apparently be regarded as zero.

In this manner, by an operation system that appropriately selects andcontrols, from a plurality of batteries in an electronic device, abattery that corresponds to a component to be used, a battery to be usedis determined and the power consumption of the other batteries not inuse is suppressed. Thus, a period for which the information terminal canbe used on a single charge can be extended. A structure of the presentinvention related to the operation system is an operation systemincluding a first battery, a second battery, a third battery, and apower supply management circuit that manages the first to thirdbatteries. The power supply management circuit wirelessly supplieselectric power from the first battery to the second battery or the thirdbattery. Alternatively, an operation system may include a first battery,a second battery, a third battery, and a control unit that manages thefirst to third batteries, and may wirelessly charge the first battery,the second battery, and the third battery at a time.

Furthermore, the power supply management circuit may operate such thatelectric power is supplied to a battery connected to a function to beused from the other batteries connected to the other functions not inuse. Owing to the operation system that appropriately selects, from aplurality of batteries in an electronic device, a battery correspondingto a component to be used and adjusts the amount of electric power ofeach battery, a period for which the function to be used can be used canbe extended. In addition, if any of the batteries is secured as anemergency power supply by the power supply management circuit, theelectronic device can be used in emergency. For a cell-phone or thelike, for example, an image is displayed on the display portion when thepower supply is turned on; accordingly, if there is not enough electricpower to display an image on the display portion, a phone call cannot bemade in some cases. In the case where the electronic device has aplurality of batteries one of which is secured as an emergency powersupply by the power supply management circuit and the emergency powersupply is available only for a communication function while electricpower supply to the display portion is in an off state, a phone call canbe made without displaying an image on the display portion.

Furthermore, if small-sized batteries are dotted in the electronicdevice and an exterior body of the device is made of a flexiblematerial, a flexible device having a complex external shape can beobtained.

Furthermore, if a wearable electronic device that is used while beingworn on the body is dotted with small-sized batteries inside, a feelingof weight can be reduced as compared to an electronic device having asingle large battery. In addition, even if the individual small-sizedbattery generates heat, it does not ruin the comfort of wearing thedevice.

Furthermore, if an artificial organ is dotted with small-sized batteriesinside the electronic device, freedom of shapes can be provided. Inaddition, if the exterior body is made of a flexible material, aflexible artificial organ can be obtained. In the case where a flexibleartificial organ is manufactured, use of a plurality of batteries ratherthan a single battery enables design of a structure that can be benteasily. In addition, an artificial organ with a thinner external shapeor a smaller artificial organ, than an artificial organ with a singlebattery, can be manufactured. In addition, if each of the plurality ofbatteries dotted in the artificial organ can be wirelessly charged, thenumber of regular removals and implantations of an artificial organbefore the battery runs down can be reduced.

Furthermore, after an artificial organ such as a pacemaker or anartificial ear is implanted under the skin, the portion where theartificial organ is implanted gets swollen, and the skin is unnaturallystretched. Many users worry about such appearance. Therefore, thethickness of an artificial organ is preferably small, even if the areais large. Providing an artificial organ with small-sized batteriesdotted about inside in order that the portion where the artificial organis implanted is prevented from being swollen is helpful.

Furthermore, since the breakage or drain of the battery of an artificialorgan for some reason may cause serious damage to the user, it ishelpful for the artificial organ to have an emergency power supply. Itis desirable that a plurality of batteries be provided in an artificialorgan and that a power supply management circuit for managing thebatteries use a battery available to transmit an emergency signal or thelike to the exterior (e.g., the user's information terminal).Determination of whether or not a battery has an abnormality isdifficult. In the case where an artificial organ determines to set acertain battery as an emergency power supply, if the battery becomesunavailable, the meaning of the emergency power supply may be lost. Itis helpful if a power supply management circuit identifies a batterywith an abnormality, stops power supply from the battery, selectsanother battery as an emergency power supply, and transmits an emergencysignal or the like. In other words, selecting batteries to be used,depending on the circumstances, by the power supply management circuitis helpful. Of course, the user can select batteries to be used, bygiving instruction to the power supply management circuit.

Furthermore, in the case where a single large-sized battery is used foran electronic device having a curved surface or complex shape, theplacement of the battery is limited, and the large-sized battery maydeteriorate the design. For a wearable electronic device such as a thinelectronic device that is used while being wrapped around the arm, inparticular, bending a large-sized battery is difficult. If a pluralityof small-sized batteries are dotted in a thin electronic device that isused while being wrapped around the arm, the individual small-sizedbattery can be incorporated in the thin electronic device without beingbent. In addition, since a wearable electronic device is close to theskin, a large-sized battery that generates heat may bring discomfort tothe user. However, if small-sized batteries are dotted about, the amountof heat per one battery can be suppressed. In addition, if small-sizedbatteries are dotted about, the risk of explosion and the like can besuppressed; therefore, the safety is higher than the case where alarge-sized battery is used.

In the case where the user carries around and drops an electronic devicehaving only a single large-sized battery, breakage of the battery makesall the functions of the electronic device unavailable. In the casewhere a plurality of small-sized batteries are included, even if one ofthem is broken, some of the functions are still available as long as atleast one of the small-sized batteries can be used. In this manner, inan electronic device including a plurality of small-sized batteries,each of which is used for a different component, some of its functionsare available even if some of its functions are broken. Thus, anelectronic device that hardly becomes out of order can be obtained.

Furthermore, even when one of the small-sized batteries is broken or itsamount of electric power becomes zero, another battery can be used as asubstitute, owing to the power supply management circuit, which makes itpossible for the electronic device to be used continuously. Furthermore,even when the amount of electric power of one of the small-sizedbatteries becomes zero, it can be wirelessly charged with electric powersupplied from a transmitting portion connected to another battery, owingto the power supply management circuit. In this manner, the electronicdevice can be used for a long period. In other words, an electronicdevice having a power supply management circuit that enables mutualsupply of electric power among a plurality of batteries can be obtained.

A battery is a device that deteriorates as the number of chargesincreases. Owing to the power supply management circuit adjusting thenumber of charges or selecting batteries to be used, the usage period ofbatteries can be extended. In addition, by monitoring the degree ofdeterioration of batteries by the power supply management circuit andappropriately selecting batteries to be used depending on the degree ofdeterioration by the power supply management circuit, the usage periodof the electronic device can be extended.

It is preferable that at least one of the plurality of small-sizedbatteries provided in the electronic device be a secondary battery thatcan be wirelessly charged.

As the secondary battery, one or more kinds selected from the followingcan be used: a lithium ion secondary battery such as a lithium polymerbattery, a lithium ion capacitor, an electric double layer capacitor,and a redox capacitor. The electronic device includes an antennawirelessly receiving electric power and a control means supplying thereceived electric power to a functional circuit.

The antenna included in the electronic device constitutes acommunication module that realizes a wireless charging function. Thecommunication module may use a charging method corresponding to astandard such as Qi or Powermat. At the time of charging, a plurality ofbatteries may be charged at a time. The antenna included in theelectronic device may constitute a communication module that realizes anear field wireless communication function.

A MEMS can be combined with the electronic device dotted withsmall-sized batteries inside. For example, an electronic deviceincluding a small-sized battery for supplying electric power to a sensorusing MEMS and a detection circuit, a small-sized battery for supplyingelectric power to a CPU, and a small-sized battery for supplyingelectric power to a memory storing data detected by the sensor can beobtained.

In the case where a plurality of kinds of sensors are included in anelectronic device, since a battery is provided for each component to beused, the user can selectively attach the sensor the user wants to useor detach the sensor. For example, if a control circuit that can controlsensors such as a pulse sensor, a temperature sensor, a positionalinformation sensor (e.g., a GPS), an acceleration sensor, and an angularvelocity sensor, and a connection portion (a connection socket) toconnect the sensor and the control circuit are provided in an electronicdevice, which is used while being wrapped around the arm, the user canselect the sensor depending on the function the user wants to use, andthe sensor may be connected to the electronic device. In that case, eachof the sensors has a small-sized battery and a regulator, and the largernumber of functions are used, the larger number of small-sized batteriesare connected. Thus, an electronic device having a plurality ofsmall-sized batteries is obtained.

If a transistor using an oxide semiconductor layer (also referred to asan OS transistor) is used for a regulator, reduction in powerconsumption can be achieved since the off-state current is small. Inparticular, a regulator (DC-DC converter) including a control circuitincluding OS transistors can operate at a temperature of 150° C. orhigher. Thus, such a DC-DC converter is preferably used for anelectronic device that is likely to operate at high temperatures.

An oxide semiconductor used for the oxide semiconductor layer to be achannel formation region of the OS transistor preferably contains atleast indium (In) or zinc (Zn). In particular, In and Zn are preferablycontained. A stabilizer for strongly bonding oxygen is preferablycontained in addition to In and Zn. As a stabilizer, at least one ofgallium (Ga), tin (Sn), zirconium (Zr), hafnium (Hf), and aluminum (Al)may be contained.

As another stabilizer, one or plural kinds of lanthanoid such aslanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium(Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy),holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium(Lu) may be contained.

As the oxide semiconductor film used for the OS transistor, for example,any of the following oxides can be used: indium oxide, tin oxide, zincoxide, an In—Zn-based oxide, a Sn—Zn-based oxide, an Al—Zn-based oxide,a Zn—Mg-based oxide, a Sn—Mg-based oxide, an In—Mg-based oxide, anIn—Ga-based oxide, an In—Ga—Zn-based oxide (also referred to as IGZO),an In—Al—Zn-based oxide, an In—Sn—Zn-based oxide, a Sn—Ga—Zn-basedoxide, an Al—Ga—Zn-based oxide, a Sn—Al—Zn-based oxide, anIn—Hf—Zn-based oxide, an In—Zr—Zn-based oxide, an In—Ti—Zn-based oxide,an In—Sc—Zn-based oxide, an In—Y—Zn-based oxide, an In—La—Zn-basedoxide, an In—Ce—Zn-based oxide, an In—Pr—Zn-based oxide, anIn—Nd—Zn-based oxide, an In—Sm—Zn-based oxide, an In—Eu—Zn-based oxide,an In—Gd—Zn-based oxide, an In—Tb—Zn-based oxide, an In—Dy—Zn-basedoxide, an In—Ho—Zn-based oxide, an In—Er—Zn-based oxide, anIn—Tm—Zn-based oxide, an In—Yb—Zn-based oxide, an In—Lu—Zn-based oxide,an In—Sn—Ga—Zn-based oxide, an In—Hf—Ga—Zn-based oxide, anIn—Al—Ga—Zn-based oxide, an In—Sn—Al—Zn-based oxide, anIn—Sn—Hf—Zn-based oxide, and an In—Hf—Al—Zn-based oxide.

For example, an In—Ga—Zn-based oxide with an atomic ratio ofIn:Ga:Zn=1:1:1, In:Ga:Zn=3:1:2, or In:Ga:Zn=2:1:3, or an oxide with anatomic ratio close to the above atomic ratios can be used.

If an oxide semiconductor film used for a channel formation regioncontains a large amount of hydrogen, the hydrogen and the oxidesemiconductor are bonded to each other, so that part of the hydrogenserves as a donor and causes generation of an electron which is acarrier. As a result, the threshold voltage of the transistor shifts inthe negative direction. It is therefore preferable that after formationof the oxide semiconductor film, dehydration treatment (dehydrogenationtreatment) be performed to remove hydrogen or moisture from the oxidesemiconductor film so that the oxide semiconductor film is highlypurified to contain impurities as little as possible.

Note that oxygen in the oxide semiconductor film is also reduced by thedehydration treatment (dehydrogenation treatment) in some cases.Accordingly, it is preferable that oxygen be added to the oxidesemiconductor film to fill oxygen vacancies increased by the dehydrationtreatment (dehydrogenation treatment). In this specification and thelike, supplying oxygen to an oxide semiconductor film may be expressedas oxygen adding treatment, or treatment for making the oxygen contentof an oxide semiconductor film be in excess of that of thestoichiometric composition may be expressed as treatment for making anoxygen-excess state.

In this manner, hydrogen or moisture is removed from the oxidesemiconductor film by the dehydration treatment (dehydrogenationtreatment) and oxygen vacancies therein are filled by the oxygen addingtreatment, whereby the oxide semiconductor film can be turned into ani-type (intrinsic) oxide semiconductor film or a substantially i-type(intrinsic) oxide semiconductor film which is extremely close to ani-type oxide semiconductor film. Note that “substantially intrinsic”means that the oxide semiconductor film contains extremely few (close tozero) carriers derived from a donor and has a carrier density which is1×10¹⁷/cm³ or lower, 1×10¹⁶/cm³ or lower, 1×10¹⁵/cm³ or lower,1×10¹⁴/cm³ or lower, 1×10¹³/cm³ or lower, lower than 8×10¹¹/cm³, orlower than 1×10¹¹/cm³. The lower limit of a carrier density is1×10⁻⁹/cm³ or higher.

Thus, the transistor including an i-type or substantially i-type oxidesemiconductor film can have extremely favorable off-state currentcharacteristics. For example, the off-state drain current of thetransistor including the oxide semiconductor film can be 1×10⁻¹⁸ A orless, preferably 1×10⁻²¹ A or less, more preferably 1×10⁻²⁴ A or less atroom temperature (approximately 25° C.), or 1×10⁻¹⁵ A or less,preferably 1×10⁻¹⁸ A or less, more preferably 1×10⁻²¹ A or less at 85°C. An off state of a transistor refers to a state where a gate voltageis much lower than the threshold voltage in an n-channel transistor.Specifically, the transistor is in an off state when the gate voltage islower than the threshold voltage by 1 V or more, 2 V or more, or 3 V ormore.

An oxide semiconductor which is formed may include a non-single-crystal,for example. An oxide semiconductor may include CAAC, for example. Notethat an oxide semiconductor including CAAC is referred to as a CAAC-OS(c-axis aligned crystalline oxide semiconductor). The CAAC-OS mayinclude a plurality of crystal parts in which c-axes are aligned in adirection parallel to a normal vector of a surface where the CAAC-OS isformed or a normal vector of a surface of the CAAC-OS.

An electronic device with a plurality of power supplies, in which abattery is provided for each of components to be used, also has acharacteristic operation system. For example, the operation systemincludes a first battery, a second battery, a third battery, and acontrol unit that controls the first to third batteries, and canwirelessly charge the first to third batteries at a time. Furthermore,the operation system includes at least a plurality of power supplies(e.g., secondary batteries) and a control unit such as a CPU, and thecontrol unit manages electric power of the plurality of power supplies.The number of control unit of the electronic device is not limited toone, and may be the same as the number of the plurality of powersupplies.

Furthermore, an operation system of an electronic device with aplurality of power supplies includes a first battery, a second battery,a third battery, and a power supply management circuit that manages thefirst to third batteries, and the first battery wirelessly supplieselectric power to the second battery or the third battery. The powersupply management circuit monitors the amount of electric power of eachbattery, and can charge one battery with electric power wirelesslysupplied from another battery automatically or by operation of the useras appropriate.

An electronic device having a plurality of batteries and a power supplymanagement circuit that enables mutual supply of electric power amongthe plurality of batteries can be provided. In that case, by replacingone of the plurality of batteries, the other batteries can be chargedwithout replacement. In addition, it is also possible to wirelesslycharge one of the plurality of batteries from an external source, thenstop the charge from the external source by the power supply managementcircuit, and wirelessly charge the other batteries inside the electronicdevice. Through repetition of the above, all the plurality of batteriescan be fully charged.

The electronic device is provided with a battery for each of thecomponents to be used, and the operation system selectively drives onlythe component to be used, whereby power consumption can be reduced.Thus, an electronic device having a novel structure can be provided.Note that the description of these effects does not preclude theexistence of other effects. One embodiment of the present invention doesnot necessarily achieve all the effects listed above. Other effects willbe apparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a block diagram illustrating one embodiment of the presentinvention;

FIG. 2 illustrates an electronic device of one embodiment of the presentinvention;

FIGS. 3A to 3C are block diagrams each illustrating one embodiment ofthe present invention;

FIGS. 4A to 4F each illustrate an electronic device of one embodiment ofthe present invention;

FIGS. 5A and 5B each illustrate an electronic device of one embodimentof the present invention;

FIG. 6 illustrates an electronic device of one embodiment of the presentinvention;

FIGS. 7A and 7B each illustrate an electronic device of one embodimentof the present invention;

FIG. 8 is a block diagram illustrating one embodiment of the presentinvention; and

FIG. 9 illustrates an electronic device of one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below in detailwith reference to the drawings. However, the present invention is notlimited to the description below, and it is easily understood by thoseskilled in the art that modes and details disclosed herein can bemodified in various ways. Furthermore, the present invention is notconstrued as being limited to description of the embodiments.

Embodiment 1

In this embodiment, an example of a device such as a portableinformation terminal will be described below.

FIG. 1 is a block diagram of a device 110.

The device 110 of this embodiment includes a control module 115, adisplay module 121, a communication module 126, and a power supplymanagement circuit 127. The control module 115 is a controller thatcontrols the entire device 110, communication, and display ofinformation on a display portion 116.

The control module 115 includes a CPU 111, a battery 112, a regulator113, a wireless receiving portion 114, and a wireless transmittingportion 128.

The display module 121 includes the display portion 116, a displaydriver circuit 119, a battery 117, a regulator 118, a wireless receivingportion 120, and a wireless transmitting portion 129. Although anexample in which the device 110 includes the display portion 116 isshown in FIG. 1, this embodiment is not limited thereto, and anotherfunctional portion such as a sensor portion can be provided in place ofthe display portion 116.

The communication module 126 includes a communication circuit 122, abattery 123, a regulator 124, a wireless receiving portion 125, and awireless transmitting portion 130.

Each module includes a regulator and a battery. Each regulator produceselectric power or a signal necessary for the respective functionalcircuit with the use of the electric power of the connected battery, andsupplies the electric power or signal to the functional circuit. Inaddition, the regulator can prevent overcharge and the like when thebattery is charged. Although an example in which a wireless receivingportion and a wireless transmitting portion are connected to oneregulator is shown in FIG. 1, a regulator connected to a wirelessreceiving portion and a regulator connected to a wireless transmittingportion may be separately provided.

In the device 110, the power supply management circuit 127 enableselectric power of the batteries in different modules to be mutuallysupplied. In addition, the power supply management circuit 127 monitorsthe amount of electric power of the batteries 112, 117, and 123, and cancharge one of the batteries with electric power wirelessly supplied fromanother battery automatically or by operation of the user asappropriate.

In the device 110, each of the modules can be turned on or turned offindependently. The operation system that selectively drives only themodule to be used can reduce power consumption of the device 110.

For example, when the user looks at information on the display portion116 without using a communication function, the communication circuit122 is in an off state where the battery 123 is not used in order thatelectric power to the communication circuit 122 is blocked in thecommunication module 126, while the display module 121 and the controlmodule 115 are in an on state.

Furthermore, for a still image, once the still image is displayed on thedisplay portion 116 with the display module 121 and the control module115 being in an on state, the still image can be kept displayed whileonly the display module 121 is in an on state even after the controlmodule 115 is turned off with the still image being displayed. Note thatwhen transistors of the display portion 116 use an oxide semiconductorlayer with low off-state current (e.g., an oxide material including In,Ga, and Zn), or when the display portion 116 includes a memory for eachof the pixels, the still image can be kept displayed for a certainperiod even when the supply of electric power from the battery 117 isblocked after the still image is displayed.

In this embodiment, an example in which the display module 121, thecontrol module 115, and the communication module 126 each have a batteryis described; however, the total number of batteries is not limited tothree. The electronic device may additionally include functional modulesand their batteries, in which case the electronic device has four ormore batteries in total.

As an example of an electronic device, an information terminal includingfour batteries is shown in FIG. 2.

In an electronic device 8000 illustrated in FIG. 2, a touch panel 8004connected to an FPC 8003, a display panel 8016 connected to an FPC 8005,a backlight unit 8007, a frame 8009, a printed board 8010, a CPU 8011, apower supply management circuit 8116, and batteries 8012 a, 8012 b, 8012c, and 8012 d are provided between an upper cover 8001 and a lower cover8002.

The shapes and sizes of the upper cover 8001 and the lower cover 8002can be changed as appropriate in accordance with the sizes of the touchpanel 8004 and the display panel 8016.

The touch panel 8004 can be a resistive touch panel or a capacitivetouch panel and may be formed so as to overlap with the display panel8016. A counter substrate (sealing substrate) of the display panel 8016can have a touch panel function. A photosensor may be provided in eachpixel of the display panel 8016 so that an optical touch panel isobtained. The touch panel 8004 is connected to a printed board via theFPC 8003, and the printed board includes the battery 8012 a, a regulator8021, a transmitting and receiving portion 8119, and the like. Note thata transmitting portion and a receiving portion may be separatelyprovided and may share some circuits and wirings, although they areshown as one component, i.e., the transmitting and receiving portion8119 for simplicity in this embodiment. The transmitting and receivingportion 8119 includes an antenna for wireless charge or an antenna forwireless transmission, and electric power is wirelessly supplied from anexternal source to the battery 8012 a via the regulator, whereby thebattery 8012 a is charged. The touch panel 8004 is driven mainly withthe use of the battery 8012 a. In addition, in response to theinstruction of the power supply management circuit 8116, electric powerof the battery 8012 a is transmitted via the transmitting and receivingportion 8119 to another battery to charge the battery.

The display panel 8016 is an active matrix liquid crystal displaymodule, and is connected to a printed board via the FPC 8005. Theprinted board includes the battery 8012 b, a regulator 8018, atransmitting and receiving portion 8120, and the like. The transmittingand receiving portion 8120 includes an antenna for wireless charge or anantenna for wireless transmission, and electric power is wirelesslysupplied from an external source to the battery 8012 b via theregulator, whereby the battery 8012 b is charged. The display panel 8016displays an image on a display region mainly with the use of the battery8012 b. In addition, in response to the instruction of the power supplymanagement circuit 8116, electric power of the battery 8012 b istransmitted via the transmitting and receiving portion 8120 to anotherbattery to charge the battery.

The backlight unit 8007 includes a light source 8008 such as an LED.Furthermore, the backlight unit 8007 is connected to a printed board viaan FPC. The printed board includes the battery 8012 c, a regulator 8017,a transmitting and receiving portion 8115, and the like. In addition, inresponse to the instruction of the power supply management circuit 8116,electric power of the battery 8012 c is transmitted via the transmittingand receiving portion 8115 to another battery to charge the battery.

Note that although a structure in which the light source 8008 isprovided over the backlight unit 8007 is illustrated in FIG. 2, oneembodiment of the present invention is not limited to this structure.For example, a structure in which the light source 8008 is provided atan end portion of the backlight unit 8007 and a light diffusion plate isfurther provided may be employed.

Note that the backlight unit 8007 may not necessarily be provided in thecase where the display panel 8016 is a display device using an organicEL element or a reflective liquid crystal display device. The backlightunit 8007 is provided in the case of a transmissive liquid crystaldisplay device or a transflective liquid crystal display device, forexample.

Note that as the display panel 8016, a display element, a display devicethat is a device including a display element, a light-emitting element,a light-emitting device that is a device including a light-emittingelement, or the like can employ various modes and can include variouselements. A display element, a display device, a light-emitting element,or a light-emitting device includes at least one of the following, forexample: an electroluminescence (EL) element (e.g., an EL elementincluding organic and inorganic materials, an organic EL element, or aninorganic EL element), an LED (e.g., a white LED, a red LED, a greenLED, or a blue LED), a transistor (a transistor that emits lightdepending on current), an electron emitter, a liquid crystal element,electronic ink, an electrophoretic element, a grating light valve (GLV),a plasma display panel (PDP), a display element using micro electromechanical system (MEMS), a digital micromirror device (DMD), a digitalmicro shutter (DMS), MIRASOL (registered trademark), an interferometricmodulator display (IMOD) element, a MEMS shutter display element, anoptical-interference-type MEMS display element, an electrowettingelement, a piezoelectric ceramic display, and a display element using acarbon nanotube. In addition to the above, a display medium whosecontrast, luminance, reflectivity, transmittance, or the like changes byelectrical or magnetic action may be included. Note that examples ofdisplay devices having EL elements include an EL display. Examples ofdisplay devices including electron emitters are a field emission display(FED) and an SED-type flat panel display (SED: surface-conductionelectron-emitter display). Examples of display devices including liquidcrystal elements include a liquid crystal display (e.g., a transmissiveliquid crystal display, a transflective liquid crystal display, areflective liquid crystal display, a direct-view liquid crystal display,or a projection liquid crystal display). Examples of a display deviceincluding electronic ink, electronic liquid powder (registeredtrademark), or electrophoretic elements include electronic paper. In thecase of a transflective liquid crystal display or a reflective liquidcrystal display, some of or all of pixel electrodes function asreflective electrodes. For example, some or all of pixel electrodes areformed to contain aluminum, silver, or the like. In such a case, amemory circuit such as an SRAM can be provided under the reflectiveelectrodes, leading to lower power consumption.

In the display panel 8016, an active matrix method in which an activeelement is included in a pixel or a passive matrix method in which anactive element is not included in a pixel can be used.

In an active matrix method, as an active element (a non-linear element),not only a transistor but also various active elements (non-linearelements) can be used. For example, an MIM (metal insulator metal), aTFD (thin film diode), or the like can also be used. Since such anelement has few numbers of manufacturing steps, manufacturing cost canbe reduced or yield can be improved. Alternatively, since the size ofthe element is small, the aperture ratio can be improved, so that powerconsumption can be reduced or higher luminance can be achieved.

As a method other than the active matrix method, the passive matrixmethod in which an active element (a non-linear element) is not used canalso be used. Since an active element (a non-linear element) is notused, the number of manufacturing steps is small, so that manufacturingcost can be reduced or yield can be improved. Alternatively, since anactive element (a non-linear element) is not used, the aperture ratiocan be improved, so that power consumption can be reduced or higherluminance can be achieved, for example.

In the case where transistors are used in the display panel 8016 and thelike, the transistors can be formed with the use of a variety ofsubstrates. The type of a substrate is not limited to a certain type. Asthe substrate, a semiconductor substrate (e.g., a single crystalsubstrate or a silicon substrate), an SOI substrate, a glass substrate,a quartz substrate, a plastic substrate, a metal substrate, a stainlesssteel substrate, a substrate including stainless steel foil, a tungstensubstrate, a substrate including tungsten foil, a flexible substrate, anattachment film, paper including a fibrous material, a base materialfilm, or the like can be used, for example. As an example of a glasssubstrate, a barium borosilicate glass substrate, an aluminoborosilicateglass substrate, a soda lime glass substrate, or the like can be given.Examples of a flexible substrate, an attachment film, a base materialfilm, or the like are as follows: plastic typified by polyethyleneterephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES); a synthetic resin such as acrylic; polypropylene;polyester; polyvinyl fluoride; polyvinyl chloride; polyamide; polyimide;aramid; epoxy; an inorganic vapor deposition film; and paper.Specifically, the use of semiconductor substrates, single crystalsubstrates, SOI substrates, or the like enables the manufacture ofsmall-sized transistors with a small variation in characteristics, size,shape, or the like and with high current capability. A circuit usingsuch transistors achieves lower power consumption of the circuit orhigher integration of the circuit.

Alternatively, a flexible substrate may be used as the substrate, andthe transistor may be provided directly on the flexible substrate.Further alternatively, a separation layer may be provided between thesubstrate and the transistor. The separation layer can be used when partor the whole of a semiconductor device formed over the separation layeris separated from the substrate and transferred onto another substrate.In such a case, the transistor can be transferred to a substrate havinglow heat resistance or a flexible substrate as well. For the aboveseparation layer, a stack including inorganic films, which are atungsten film and a silicon oxide film, or an organic resin film ofpolyimide or the like formed over a substrate can be used, for example.

In other words, a transistor may be formed using one substrate, and thentransferred to another substrate. Examples of a substrate to which atransistor is transferred include, in addition to the above substrateover which the transistor can be formed, a paper substrate, a cellophanesubstrate, an aramid film substrate, a polyimide film substrate, a stonesubstrate, a wood substrate, a cloth substrate (including a naturalfiber (e.g., silk, cotton, or hemp), a synthetic fiber (e.g., nylon,polyurethane, or polyester), a regenerated fiber (e.g., acetate, cupra,rayon, or regenerated polyester), and the like), a leather substrate,and a rubber substrate. When such a substrate is used, a transistor withexcellent properties or a transistor with low power consumption can beformed, a device with high durability, high heat resistance can beprovided, or reduction in weight or thickness can be achieved.

In the case where transistors are used in the display panel 8016 and thelike, transistors with a variety of configurations can be used. There isno limitation on the type of transistors. For example, a transistorincluding a single-crystal silicon or a non-single-crystal semiconductorfilm typified by amorphous silicon, polycrystalline silicon,microcrystalline (also referred to as microcrystal, nanocrystal, orsemi-amorphous) silicon, or the like can be used as a transistor.Alternatively, a thin film transistor (TFT) whose semiconductor film isthinned can be used. In the case of using the TFT, there are variousadvantages. For example, since the TFT can be formed at temperaturelower than that of the case of using single-crystal silicon,manufacturing cost can be reduced or a manufacturing apparatus can bemade larger. Since the manufacturing apparatus is made larger, the TFTcan be formed using a large substrate. Therefore, many display devicescan be formed at the same time at low cost. In addition, a substratehaving low heat resistance can be used because of low manufacturingtemperature. Therefore, the transistor can be formed using alight-transmitting substrate. Alternatively, transmission of light in adisplay element can be controlled by using the transistor formed usingthe light-transmitting substrate. Alternatively, part of a film includedin the transistor can transmit light because the thickness of thetransistor is small. Therefore, the aperture ratio can be improved.

Note that when a catalyst (e.g., nickel) is used in the case of formingpolycrystalline silicon, crystallinity can be further improved and atransistor having excellent electric characteristics can be formed.Accordingly, a gate driver circuit (e.g., a scan line driver circuit), asource driver circuit (e.g., a signal line driver circuit), and a signalprocessing circuit (e.g., a signal generation circuit, a gammacorrection circuit, or a DA converter circuit) can be formed using thesame substrate as a pixel portion.

Note that when a catalyst (e.g., nickel) is used in the case of formingmicrocrystalline silicon, crystallinity can be further improved and atransistor having excellent electric characteristics can be formed. Inthis case, crystallinity can be improved by just performing heattreatment without performing laser irradiation. Accordingly, a gatedriver circuit (e.g., a scan line driver circuit) and part of a sourcedriver circuit (e.g., an analog switch) can be formed over the samesubstrate. Note that when laser irradiation for crystallization is notperformed, unevenness in crystallinity of silicon can be suppressed.Therefore, high-quality images can be displayed. Note that it ispossible to manufacture polycrystalline silicon or microcrystallinesilicon without a catalyst (e.g., nickel).

Note that although preferably, crystallinity of silicon is improved topolycrystal, microcrystal, or the like in the whole panel, the presentinvention is not limited to this. Crystallinity of silicon may beimproved only in part of the panel. Selective increase in crystallinitycan be achieved by selective laser irradiation or the like. For example,only a peripheral driver circuit region excluding pixels may beirradiated with laser light. Alternatively, only a region of a gatedriver circuit, a source driver circuit, or the like may be irradiatedwith laser light. Alternatively, only part of a source driver circuit(e.g., an analog switch) may be irradiated with laser light.Accordingly, crystallinity of silicon can be improved only in a regionin which a circuit needs to be operated at high speed. Since a pixelregion is not particularly needed to be operated at high speed, even ifcrystallinity is not improved, the pixel circuit can be operated withoutproblems. Thus, a region whose crystallinity is improved is small, sothat manufacturing steps can be decreased. Thus, throughput can beincreased and manufacturing cost can be reduced. Alternatively, sincethe number of necessary manufacturing apparatus is small, manufacturingcost can be reduced.

As the transistors, for example, transistors including a compoundsemiconductor (e.g., SiGe, and GaAs) or an oxide semiconductor (e.g.,Zn—O, In—Ga—Zn—O, In—Zn—O (IZO (registered trademark)), In—Sn—O (ITO),Sn—O, Ti—O, Al—Zn—Sn—O (AZTO), In—Sn—Zn—O (ITZO (registered trademark))can be used. Alternatively, a thin film transistor obtained by thinningany of the compound semiconductors or the oxide semiconductors can beused. Since manufacturing temperature can be lowered, such a transistorcan be formed at room temperature, for example. Accordingly, thetransistor can be formed directly on a substrate having low heatresistance, such as a plastic substrate or a film substrate. Note thatsuch a compound semiconductor or an oxide semiconductor can be used notonly for a channel portion of the transistor but also for otherapplications. For example, such a compound semiconductor or an oxidesemiconductor can be used for a wiring, a resistor, a pixel electrode, alight-transmitting electrode, or the like. Since such an element can beformed at the same time as the transistor, cost can be reduced.

Note that for example, a transistor or the like formed by an inkjetmethod or a printing method can be used as a transistor. Accordingly, atransistor can be formed at room temperature, can be formed at a lowvacuum, or can be formed using a large substrate. Therefore, thetransistor can be formed without use of a mask (reticle), so that thelayout of the transistor can be easily changed. Alternatively, since thetransistor can be formed without use of a resist, material cost isreduced and the number of steps can be reduced. Furthermore, since afilm can be formed where needed, a material is not wasted as compared toa manufacturing method by which etching is performed after the film isformed over the entire surface; thus, costs can be reduced.

Note that for example, a transistor or the like including an organicsemiconductor or a carbon nanotube can be used as a transistor.Accordingly, such a transistor can be formed using a substrate which canbe bent. A device including a transistor which includes an organicsemiconductor or a carbon nanotube can resist a shock.

In the case where transistors are used in circuits included in thedisplay module 121, the control module 115, the communication module126, the electronic device 8000, and the like, transistors with avariety of other configurations can be used. For example, a MOStransistor, a junction transistor, a bipolar transistor, or the like canbe used as a transistor. By using a MOS transistor as a transistor, thesize of the transistor can be reduced. Thus, a large number oftransistors can be mounted. By using a bipolar transistor as atransistor, a large amount of current can flow. Thus, a circuit can beoperated at high speed. Note that a MOS transistor and a bipolartransistor may be formed over one substrate. Thus, reduction in powerconsumption, reduction in size, high speed operation, and the like canbe realized.

Alternatively, for example, a transistor with a multi-gate structurehaving two or more gate electrodes can be used as a transistor. With themulti-gate structure, a structure where a plurality of transistors areconnected in series is provided because channel regions are connected inseries. Thus, with the multi-gate structure, the amount of off-statecurrent can be reduced and the withstand voltage of the transistor canbe increased (the reliability can be improved). Alternatively, with themulti-gate structure, drain-source current does not change much even ifdrain-source voltage changes when the transistor operates in asaturation region, so that a flat slope of voltage-currentcharacteristics can be obtained. By utilizing the flat slope of thevoltage-current characteristics, an ideal current source circuit or anactive load having an extremely large resistance can be realized.Accordingly, a differential circuit, a current mirror circuit, or thelike having excellent properties can be realized.

Note that a transistor with a structure where gate electrodes are formedabove and below a channel can be used, for example. With the structurewhere the gate electrodes are formed above and below the channel, acircuit structure where a plurality of transistors are connected inparallel is provided. Thus, a channel region is increased, so that theamount of current can be increased. Alternatively, by using thestructure where gate electrodes are formed above and below the channel,a depletion layer can be easily formed, so that subthreshold swing canbe improved.

Note that as a transistor, for example, it is possible to use atransistor with a structure where a gate electrode is formed above achannel region, a structure where a gate electrode is formed below achannel region, a staggered structure, an inverted staggered structure,a structure where a channel region is divided into a plurality ofregions, a structure where channel regions are connected in parallel orin series, or the like. A transistor with any of a variety of structuressuch as a planar type, a FIN-type, a Tri-Gate type, a top-gate type, abottom-gate type, a double-gate type (with gates above and below achannel), and the like can be used.

The frame 8009 has a function of protecting the display panel 8016. Theframe 8009 can also function as a radiator plate. Furthermore, the frame8009 may incorporate an antenna of any of the receiving portions.

A control unit includes over the printed board 8010 the CPU 8011, thebattery 8012 d, a regulator 8013, a transmitting and receiving portion8114, and a signal processing circuit for outputting a video signal anda clock signal. Although an example in which the power supply managementcircuit 8116 is provided over the same printed board 8010 is shown, thisembodiment is not limited thereto. The CPU 8011 may have the samefunction as the power supply management circuit 8116 and be formed intoone chip. For the power supply management circuit 8116 that monitors andmanages a plurality of batteries, a power supply to supply the electricpower thereto may be separately provided; however, in this embodiment,the battery 8012 d provided over the same printed board 8010 serves asthe main power supply of the power supply management circuit 8116.Furthermore, the amount of electric power of the batteries 8012 a, 8012b, and 8012 c provided over the other printed boards is monitored by thepower supply management circuit 8116 through wireless communicationusing the transmitting and receiving portion 8114, and the batteries8012 a, 8012 b, and 8012 c can be used as the auxiliary power supplies.For example, when the remaining amount of electric power of the battery8012 d is reduced, electric power from the batteries 8012 a, 8012 b, and8012 c may be wirelessly transmitted to the battery 8012 d, whereby thebattery 8012 d is charged.

At the time of charging from an external source (e.g., a charger), thetransmitting and receiving portions may receive electric power at atime. When an electronic device is wirelessly charged, the electronicdevice is not always charged smoothly depending on how the electronicdevice is placed on the charger or how the electronic device and thecharger are positioned. Since the electronic device 8000 has a pluralityof transmitting and receiving portions, if the positions of thetransmitting and receiving portions are scattered, any one of thetransmitting and receiving portions can receive electric powerregardless of how the electronic device 8000 is placed on the charger.As long as any one of the transmitting and receiving portions canreceive electric power and one battery is charged, the other battery orbatteries can be charged with electric power from the charged onebattery, owing to the power supply management circuit 8116. As a result,all the batteries can be fully charged.

Since the electronic device 8000 is an information terminal, it has acommunication module as a communication function. That is, thecommunication module that realizes a wireless charging function isincorporated. Furthermore, the electronic device 8000 may incorporate acommunication module that realizes a near field wireless communicationfunction, which enables a phone call to be made. In that case, thecommunication module may also include a battery. The electronic device8000 can include another function such as a sensor (a sensor having afunction of measuring force, displacement, position, speed,acceleration, angular velocity, rotational frequency, distance, light,liquid, magnetism, temperature, chemical substance, sound, time,hardness, electric field, current, voltage, electric power, radiation,flow rate, humidity, gradient, oscillation, odor, or infrared rays), anda microphone.

One printed board is used for each of the functional circuits, andregulators and batteries are incorporated in order that an optimal poweroutput corresponding to each of the functional circuits is possible. Inaddition, the distance between the battery and the functional circuit isclose, and a lead wiring can be short, which can reduce powerconsumption.

Although an example in which one printed board is used for each of thefunctions and a plurality of printed boards are used in total is shownin FIG. 2, this embodiment is not limited thereto. All the functionalcircuits may be provided over one printed board, in which case aplurality of batteries are provided over the one printed board. Aplurality of functions may be provided over one printed board, and atthat time, a single battery instead of a plurality of batteries may beprovided. Each of the display panel 8016, the touch panel 8004, and thebacklight unit 8007 in FIG. 2 is electrically connected to the controlunit via a wiring cord or an FPC not shown in FIG. 2. Furthermore, sincethe electronic device 8000 in FIG. 2 has the transmitting and receivingcircuit and the like over each of the printed boards, the printed boardsneed not be connected with each other via wirings or the like fordriving. Since wireless communication and wireless charge are possibleamong the circuits, arrangement of wiring cords and design of connectorscan be simplified, which can improve the degree of freedom in design.

Furthermore, the electronic device 8000 may further be provided with aslot for insertion of a SIM card, a connector portion for connecting aUSB device such as a USB memory.

As described above, in the electronic device 8000, a battery is providedfor each of the units (modules or functions) to be used, and a pluralityof power supplies are managed by the power supply management circuit8116. The electronic device 8000 having a plurality of power supplies isprovided with the operation system that selectively drives only thefunction to be used, whereby power consumption can be reduced. Inaddition, the power supply management circuit 8116 monitors the amountof electric power of each battery, and can charge one battery withelectric power wirelessly supplied from another battery automatically orby operation of the user as appropriate. Owing to the operation systemthat appropriately selects, from the plurality of batteries in theelectronic device, a battery corresponding to a component to be used,and adjusts the amount of electric power of each battery; a period forwhich the function to be used can be used can be extended.

Furthermore, each of the batteries is provided with a communicationmodule that realizes a wireless charging function, and charging of theplurality of batteries at a time can be performed. In addition, thetransmitting and receiving portion is included and the power supplymanagement circuit can adjust the amount of electric power; therefore,mutual supply of electric power among the batteries is possible.

Although an example in which the electronic device 8000 has a box-likeshape is described in this embodiment, one embodiment of the inventionis not limited thereto. The electronic device may have a complex shape.In the case where an electronic device with a complex shape ismanufactured, a plurality of small-sized batteries are placed inpredetermined places as appropriate, whereby the degree of freedom indesign of the electronic device can be increased.

Embodiment 2

In Embodiment 1, an example of an electronic device in which a battery,a wireless receiving portion, and a CPU are mounted on one printed boardand a plurality of printed boards are provided is described. InEmbodiment 2, an example in which a regulator 1188 is formed over asubstrate 1190 with a CPU, and a small battery is connected to the CPUvia the regulator 1188 will be described. The regulator 1188 produceselectric power or a signal necessary for each functional circuit from aconnected power supply (e.g., a battery) and supplies the electric poweror signal. FIG. 3A shows an example in which the regulator 1188 and theCPU are formed over the substrate 1190.

The CPU will be described below.

FIG. 3A is a block diagram illustrating a specific structure of a CPU.The CPU illustrated in FIG. 3A includes an arithmetic logic unit (ALU)1191, an ALU controller 1192, an instruction decoder 1193, an interruptcontroller 1194, a timing controller 1195, a register 1196, a registercontroller 1197, a bus interface (Bus I/F) 1198, a rewritable ROM 1199,and an ROM interface (ROM I/F) 1189 over a substrate 1190. Asemiconductor substrate, an SOI substrate, a glass substrate, or thelike is used as the substrate 1190. The ROM 1199 and the ROM interface1189 may each be provided over a separate chip. Obviously, the CPUillustrated in FIG. 3A is only an example in which the structure issimplified, and an actual CPU has various structures depending on theapplication.

An instruction that is input to the CPU through the bus interface 1198is input to the instruction decoder 1193 and decoded therein, and then,input to the ALU controller 1192, the interrupt controller 1194, theregister controller 1197, and the timing controller 1195.

The ALU controller 1192, the interrupt controller 1194, the registercontroller 1197, and the timing controller 1195 conduct various controlsin accordance with the decoded instruction. Specifically, the ALUcontroller 1192 generates signals for controlling the operation of theALU 1191. While the CPU is executing a program, the interrupt controller1194 processes an interrupt request from an external input/output deviceor a peripheral circuit depending on its priority or a mask state. Theregister controller 1197 generates an address of the register 1196, andreads/writes data from/to the register 1196 depending on the state ofthe CPU.

The timing controller 1195 generates signals for controlling operationtimings of the ALU 1191, the ALU controller 1192, the instructiondecoder 1193, the interrupt controller 1194, and the register controller1197. For example, the timing controller 1195 includes an internal clockgenerator for generating an internal clock signal CLK2 on the basis of areference clock signal CLK1, and supplies the internal clock signal CLK2to the above circuits.

In the CPU illustrated in FIG. 3A, a memory cell is provided in theregister 1196. A memory cell including a transistor using an oxidesemiconductor layer can be used as the memory cell of the register 1196.

In the CPU illustrated in FIG. 3A, the register controller 1197 selectsan operation of holding data in the register 1196 in accordance with aninstruction from the ALU 1191. That is, the register controller 1197selects whether data is held by a flip-flop or by a capacitor in thememory cell included in the register 1196. When data holding by theflip-flop is selected, a power supply voltage is supplied to the memorycell in the register 1196. When data holding by the capacitor isselected, the data is rewritten in the capacitor, and supply of powersupply voltage to the memory cell in the register 1196 can be stopped.

The power supply can be stopped by providing a switching element betweena memory cell group and a node to which a power supply potential VDD ora power supply potential VSS is supplied, as illustrated in FIG. 3B orFIG. 3C. Circuits illustrated in FIGS. 3B and 3C are described below.

FIGS. 3B and 3C each illustrate an example of a configuration of amemory circuit including a transistor including an oxide semiconductorlayer as a switching element for controlling supply of a power supplypotential to a memory cell.

The memory device illustrated in FIG. 3B includes a switching element1141 and a memory cell group 1143 including a plurality of memory cells1142. Each of the memory cells 1142 included in the memory cell group1143 is supplied with the high-level power supply potential VDD via theswitching element 1141. Furthermore, each of the memory cells 1142included in the memory cell group 1143 is supplied with a potential of asignal IN and the low-level power supply potential VSS.

In FIG. 3B, a transistor using an oxide semiconductor layer is used asthe switching element 1141, and the switching of the transistor iscontrolled by a signal Sig A supplied to a gate electrode layer thereof.

Note that FIG. 3B shows the structure in which the switching element1141 includes only one transistor; however, without particularlimitation thereon, the switching element 1141 may include a pluralityof transistors. In the case where the switching element 1141 includes aplurality of transistors which serves as switching elements, theplurality of transistors may be connected to each other in parallel, inseries, or in combination of parallel connection and serial connection.

Although the switching element 1141 controls the supply of thehigh-level power supply potential VDD to each of the memory cells 1142included in the memory cell group 1143 in FIG. 3B, the switching element1141 may control the supply of the low-level power supply potential VSS.

In FIG. 3C, an example of a memory device in which each of the memorycells 1142 included in the memory cell group 1143 is supplied with thelow-level power supply potential VSS via the switching element 1141 isillustrated. The supply of the low-level power supply potential VSS toeach of the memory cells 1142 included in the memory cell group 1143 canbe controlled by the switching element 1141.

When a switching element is provided between a memory cell group and anode to which the power supply potential VDD or the power supplypotential VSS is supplied, data can be held even in the case where anoperation of a CPU is temporarily stopped and the supply of the powersupply voltage is stopped; accordingly, power consumption can bereduced. Specifically, for example, while the user of a personalcomputer does not input data to an input device such as a keyboard, theoperation of the CPU can be stopped, so that the power consumption canbe reduced.

Although the CPU is given as an example, the transistor can also beapplied to an LSI such as a digital signal processor (DSP), a customLSI, or a field programmable gate array (FPGA).

This embodiment can be freely combined with any of the otherembodiments.

Embodiment 3

In this embodiment, electronic devices each of which is one embodimentof the present invention will be described with reference to FIGS. 4A to4F.

FIGS. 4A to 4F illustrate electronic devices. These electronic devicescan include a housing 5000, a display portion 5001, a speaker 5003, anLED lamp 5004, operation keys 5005 (including a power switch or anoperation switch), a connection terminal 5006, a sensor 5007 (a sensorhaving a function of measuring force, displacement, position, speed,acceleration, angular velocity, rotational frequency, distance, light,liquid, magnetism, temperature, chemical substance, sound, time,hardness, electric field, current, voltage, electric power, radiation,flow rate, humidity, gradient, oscillation, odor, or infrared ray), amicrophone 5008, and the like.

FIG. 4A shows a mobile computer, which can include a switch 5009, aninfrared port 5010, and the like in addition to the above components.FIG. 4B shows a portable image reproducing device (e.g., a DVDreproducing device) provided with a memory medium, which can include asecond display portion 5002, a memory medium reading portion 5011, andthe like in addition to the above components. FIG. 4C shows agoggle-type display, which can include a second display portion 5002, asupport portion 5012, an earphone 5013, and the like in addition to theabove components. FIG. 4D shows a portable game machine, which caninclude the memory medium reading portion 5011 and the like in additionto the above components. FIG. 4E shows a digital camera having atelevision reception function, which can include an antenna 5014, ashutter button 5015, an image receiving portion 5016, and the like inaddition to the above components. FIG. 4F shows a portable game machine,which can include the second display portion 5002, the memory mediumreading portion 5011, and the like in addition to the above components.

The electronic devices illustrated in FIGS. 4A to 4F can have a varietyof functions such as a function of displaying a variety of information(e.g., a still image, a moving image, and a text image) on a displayportion, a touch panel function, a function of displaying a calendar,date, time, and the like, a function of controlling processing with avariety of software (programs), a wireless communication function, afunction of being connected to a variety of computer networks with awireless communication function, a function of transmitting andreceiving a variety of data with a wireless communication function, anda function of reading program or data stored in a recording medium anddisplaying the program or data on a display portion. Furthermore, theelectronic device including a plurality of display portions can have afunction of displaying image information mainly on one display portionwhile displaying text information on another display portion, a functionof displaying a three-dimensional image by displaying images whereparallax is considered on a plurality of display portions, or the like.Furthermore, the electronic device including an image receiving portioncan have a function of photographing a still image, a function ofphotographing a moving image, a function of automatically or manuallycorrecting a photographed image, a function of storing a photographedimage in a memory medium (an external memory medium or a memory mediumincorporated in the camera), a function of displaying a photographedimage on the display portion, or the like. Note that functions which canbe provided for the electronic devices illustrated in FIGS. 4A to 4F arenot limited to the above, and the electronic devices can have a varietyof functions.

Each of the electronic devices described in this embodiment incorporatesa plurality of batteries and has a wireless receiving portion capable ofwireless charging. In addition, the electronic device has a power supplymanagement circuit (including a power supply monitoring circuit) formanaging the plurality of batteries. In addition, the electronic devicehas transmitting portions and receiving portions that perform wirelesscharging among different batteries, and the power supply managementcircuit selects the battery to be charged or used, depending on thecircumstances.

Usage examples of the electronic device are illustrated in FIGS. 5A and5B.

FIG. 5A shows an example where an information terminal is operated in amoving object such as a car.

The numeral 5103 indicates a steering wheel, which includes an antennainside. The antenna in the steering wheel 5103 can supply electric powerto an electronic device 5100. The electronic device 5100 has a pluralityof batteries, and at least one of the batteries is charged by wirelesscharging. The steering wheel 5103 may be provided with a jig that canfix the electronic device 5100. If the electronic device 5100 is fixedon the steering wheel 5103, the user can make a phone call or avideo-phone call without using his/her hands. Furthermore, through voiceauthentication with the use of a microphone provided in the electronicdevice 5100, the car can be driven by a voice of the driver.

For example, by operating the electronic device 5100 while the car isparked, the positional information can be displayed on a display portion5102. Furthermore, information not displayed on a display portion 5101of the car, such as engine speed, steering wheel angle, temperature, andtire pressure may be displayed on the display portion 5102. The displayportion 5102 has a touch input function. Furthermore, one or morecameras to image the outside of the car can be used to display theoutside image on the display portion 5102. That is, the display portion5102 can be used as a back monitor, for example. Furthermore, forpreventing drowsy driving, the electronic device 5100 may operate asfollows, for example: while wirelessly receiving information such as thedriving speed from the car to monitor the driving speed, the electronicdevice 5100 images the driver at the time of driving and when a periodfor which the driver closes his/her eyes is long, it vibrates, beeps, orplays music (depending on the setting that can be selected by the driveras appropriate). Furthermore, by stopping imaging the driver while thecar is parked, power consumption can be reduced. In addition, thebatteries of the electronic device 5100 may be wirelessly charged whilethe car is parked.

The electronic device 5100 is expected to be used in a variety of waysin a moving object such as a car, as described above, and is desired toincorporate a number of sensors and a plurality of antennas that enablevarious functions thereof. Although a moving object such as a car has apower supply, the power supply is limited. As the electric power todrive the moving object is considered, it is preferable that theelectric power used for the electronic device 5100 be as low aspossible. For an electric vehicle, in particular, power consumed by theelectronic device 5100 may decrease the travel distance. Even if theelectronic device 5100 has a variety of functions, it is not often thatall the functions are used at a time, and only one or two functions areusually used as necessary. In the case where the electronic device 5100including a plurality of batteries, each of which is prepared for adifferent function, has a variety of functions, only the function to beused is turned on and electric power is supplied thereto from a batterycorresponding to that function; whereby, power consumption can bereduced. Furthermore, batteries corresponding to the functions not inuse, among the plurality of batteries, can be wirelessly charged from anantenna provided in the car.

FIG. 5B illustrates an example in which an information terminal isoperated in an airplane or the like. Since a period in which anindividual can use his/her own information terminal is limited in anairplane or the like, the airplane is desired to be equipped withinformation terminals that the passengers can use when the flight islong.

An electronic device 5200, having a display portion 5202 that displaysimages such as a movie, a game, and a commercial, is an informationterminal with which the current flying location and the remaining flighttime can be obtained in real time, owing to its communication function.The display portion 5202 has a touch input function.

The electronic device 5200 can be fit into a depressed portion in a seat5201, and an antenna installation portion 5203 is provided in a positionthat overlaps with the electronic device 5200, whereby the electronicdevice 5200 can be wirelessly charged while it is fit into the depressedportion. Furthermore, the electronic device 5200 can function as atelephone or communication tool when the user is sick and wants tocontact a flight attendant, for example. If the electronic device 5200has a translation function, the user can communicate with a flightattendant by using the display portion 5202 of the electronic device5200 even when the user and the flight attendant speak differentlanguages. Furthermore, passengers seated next to one another who speakdifferent languages can communicate by using the display portion 5202 ofthe electronic device 5200. In addition, the electronic device 5200 canfunction as a message board, displaying a message in English such as“please do not disturb” on the display portion 5202 while the user isasleep, for example.

The electronic device 5200 has a plurality of batteries each of which isfor a different function, and only the function to be used is turned onwhile the other functions not in use are in an off state, whereby powerconsumption can be reduced. Furthermore, among the plurality ofbatteries, batteries corresponding to the functions not in operation canbe wirelessly charged from the antenna installation portion 5203.

It is difficult to carry a dangerous object on an airplane. Theelectronic device 5200 having a plurality of small-sized batteries ishighly safe, and even if one of the batteries explodes, the damage canbe minimized. In addition, even if one battery becomes unavailablebecause of failure, explosion, or breakage, some of the functions of theelectronic device can still be used by utilizing the other batteries.

The plurality of batteries of the electronic device 5200 provided overthe plurality of seats may be designed such that they can be used inemergency when an airplane has an electrical problem. Since all theelectronic devices 5200, each of which is provided for each of theplurality of seats, are the same products having the same design, asystem may be constructed such that the electronic devices 5200 can beconnected in series as an emergency power supply.

As the plurality of small-sized batteries of the electronic device 5200,one or more kinds selected from the following can be used: a lithium ionsecondary battery such as a lithium polymer battery, a lithium ioncapacitor, an electric double layer capacitor, and a redox capacitor.

The structure described in this embodiment can be used in appropriatecombination with the structure described in any of the otherembodiments.

Embodiment 4

In this embodiment, an example of an artificial organ will be described.

FIG. 6 is a cross-sectional schematic view of an example of a pacemaker.

A pacemaker body 5300 includes at least batteries 5301 a and 5301 b, aregulator, a power supply management circuit 5307, a control circuit, anantenna 5304, a wire 5302 reaching a right atrium, and a wire 5303reaching a right ventricle.

The pacemaker body 5300 is implanted in the body by surgery, and the twowires pass through a subclavian vein 5305 and a superior vena cava 5306of the human body, with the end of one of which placed in the rightventricle and the end of the other of which placed in the right atrium.

The antenna 5304 can receive electric power, and the plurality ofbatteries 5301 a and 5301 b are charged with the electric power, whichcan reduce the frequency of replacing the pacemaker. Since the pacemakerbody 5300 has a plurality of batteries, the safety is high, and evenwhen one of the batteries fails, the other can function. In this manner,the plurality of batteries function as auxiliary power supplies.Furthermore, the power supply management circuit 5307 may set thebattery 5301 a as an emergency power supply and the other battery 5301 bto be used mainly. In the case where the battery 5301 b is broken ordrained for some reason, it is desirable that an emergency signal or thelike be transmitted to the external (e.g., an information terminal ofthe user, or a neighbor medical institution), with the use of thebattery 5301 a. Since the breakage or drain of the battery of apacemaker for some reason may cause serious damage to the user, it ishelpful for the pacemaker to have an emergency power supply.Furthermore, if the battery to be provided in the pacemaker is furtherdivided into a plurality of thin batteries to be mounted on a printedboard where control circuits including a CPU and the like are provided,the pacemaker body 5300 can be smaller in size and thickness.

In addition to the antenna 5304 that can receive electric power, anantenna that can transmit a physiological signal may be provided for thepacemaker. For example, a system that monitors the cardiac activity,capable of monitoring physiological signals such as pulses, respiratoryrate, heart rate, and body temperature with an external monitoringdevice may be constructed.

If the pacemaker can be small in size and thickness according to thisembodiment, a protrusion generated in the portion where the pacemakerbody 5300 is implanted can be unnoticeably small.

Note that how the pacemaker is placed here is just an example, and itcan be changed in various ways depending on the heart disease.

Furthermore, this embodiment is not limited to the pacemaker. Anartificial ear is an artificial organ that is more widely used than thepacemaker. An artificial ear converts a sound into an electric signaland directly stimulates the auditory nerve with a stimulus device in thecochlea.

An artificial ear includes a first device implanted deep in the ear bysurgery and a second device that picks up sounds with a microphone andsends them to the implanted first device. The first device and thesecond device are not electrically connected to each other, andtransmission and reception between the two are conducted wirelessly. Thefirst device includes at least an antenna that receives an electricsignal converted from a sound and a wire that reaches the cochlea. Thesecond device includes at least a sound processing portion forconverting a sound into an electric signal and a transmitting circuitthat transmits the electric signal to the first device.

In this embodiment, a small-sized battery is provided in each of thefirst device and the second device, whereby the artificial ear can bereduced in size.

Since artificial ears are often implanted by surgery in childhood,reduction in size is desired.

If reduction in size of an artificial ear is achieved by thisembodiment, a protrusion generated in the portion where the artificialear is implanted can be unnoticeably small.

The structure described in this embodiment can be used in appropriatecombination with the structure described in any of the otherembodiments.

Embodiment 5

In this embodiment, a wearable electronic device will be described.

In the case where an electronic device with a complex shape ismanufactured, a plurality of small-sized batteries are placed inpredetermined places as appropriate, whereby the degree of freedom indesign of the electronic device can be increased. As shown in FIG. 7A,an electronic device 5400 has a cylindrical form. In order for theelectronic device 5400 to be worn on the human body, a plurality ofbatteries rather than a single battery are appropriately placed, wherebya feeling of the weight can be reduced. Furthermore, if the device has anumber of functions, consumption of a battery in a standby stateincreases; therefore, batteries for the respective functions areprepared. In the case where the electronic device 5400 having aplurality of batteries has a variety of functions, only the function tobe used is turned on and electric power is supplied from the batterycorresponding to the function, whereby power consumption can be reduced.

The electronic device 5400 is worn on the left upper arm, over a clothes5401, as shown in FIG. 7A. Examples of the clothes 5401 include clotheswith sleeves, such as a military uniform, an assault jacket, a suitjacket, a uniform, and space suits. There is no particular limitation onhow to wear the electronic device 5400, and examples of ways to wear itinclude sewing it on a portion of clothes that overlaps with the upperarm, attaching it with a Velcro fastener (registered trademark) or thelike provided on a portion of clothes that overlaps with the upper arm,fixing it with a band, a clasp, or the like, and binding a band-likeleaf spring around an upper arm.

The electronic device 5400 has an antenna. A perspective view in whichthe electronic device 5400 is worn on the skin and wirelessly charged isshown in FIG. 7B. In FIG. 7B, the electronic device 5400 is worn on anupper arm 5402. A surface of the electronic device 5400 that is to be incontact with the skin is preferably formed using a skin-friendly film ora natural material such as leather, paper, and fabric. The numeral 5412indicates an electric power transmission device that can wirelesslycharge the electronic device 5400 with the use of a radio wave 5413.

When an electronic device is wirelessly charged, the electronic deviceis not always charged smoothly depending on the positional relationbetween a charger and the electronic device. Since the electronic device5400 has a plurality of transmitting and receiving portions, if thepositions of the transmitting and receiving portions are scattered, anyone of the transmitting and receiving portions can receive electricpower regardless of the direction of the electronic device 5400 withrespect to the charger. As long as any one of the transmitting andreceiving portions can receive electric power and one battery ischarged, the other batteries can be wirelessly charged with electricpower from the charged one battery, owing to the power supply managementcircuit. As a result, all the batteries can be fully charged. For awearable electronic device in particular, capability of being chargedwhile worn on the human body is desired. Thus, it is helpful for awearable electronic device to have a plurality of batteries and aplurality of transmitting and receiving portions, with the power supplymanagement circuit enabling charging of any of them freely.

When provided with an antenna or a circuit that can transmit and receiveother data, the electronic device can transmit and receive other data aswell as electric power. For example, the electronic device 5400 can alsobe used like a smartphone.

The structure described in this embodiment can be used in appropriatecombination with the structure described in any of the otherembodiments.

Embodiment 6

In this embodiment, an example of a device such as a portableinformation terminal will be described below.

FIG. 8 is a block diagram of a device 10.

The device 10 of this embodiment includes a control module 15, a displaymodule 21, and a communication module 26. The control module 15 is acontroller that controls the entire device 10, communication, anddisplay of information on a display portion 16.

The control module 15 includes a CPU 11, a battery 12, a regulator 13,and a wireless receiving portion 14.

The display module 21 includes a display portion 16, a display drivercircuit 19, a battery 17, a regulator 18, and a wireless receivingportion 20. Although an example in which the device 10 includes thedisplay portion 16 is shown in FIG. 8, this embodiment is not limitedthereto, and another functional portion such as a sensor portion can beprovided in place of the display portion 16, for example.

The communication module 26 includes a communication circuit 22, abattery 23, a regulator 24, and a wireless receiving portion 25.

Each module includes a regulator and a battery. Each regulator produceselectric power or a signal necessary for the respective functionalcircuit with the use of the electric power of the connected battery, andsupplies the electric power or signal to the functional circuit. Inaddition, the regulator can prevent overcharge and the like when thebattery is charged.

In the device 10, each of the modules can be turned on or turned offindependently. The operation system that selectively drives only themodule to be used can reduce power consumption of the device 10.

For example, when the user looks at information on the display portion16 without using a communication function, the communication circuit 22is in an off state where the battery 23 is not used in order thatelectric power to the communication circuit 22 is blocked in thecommunication module 26, while the display module 21 and the controlmodule 15 are in an on state.

Furthermore, for a still image, once the still image is displayed on thedisplay portion 16 with the display module 21 and the control module 15being in an on state, the still image can be kept displayed while onlythe display module 21 is in an on state even after the control module 15is turned off with the still image being displayed. Note that whentransistors of the display portion 16 use an oxide semiconductor layerwith low off-state current (e.g., an oxide material including In, Ga,and Zn), or when the display portion 16 includes a memory for each ofthe pixels, the still image can be kept displayed for a certain periodeven when the supply of electric power from the battery 17 is blockedafter the still image is displayed.

In this embodiment, an example in which the display module 21, thecontrol module 15, and the communication module 26 each have a batteryis described; however, the total number of batteries is not limited tothree. The electronic device may additionally include functional modulesand their batteries, in which case the electronic device has four ormore batteries in total.

As an example of an electronic device, an information terminal includingfour batteries is shown in FIG. 9.

In an electronic device 8000 illustrated in FIG. 9, a touch panel 8004connected to an FPC 8003, a display panel 8016 connected to an FPC 8005,a backlight unit 8007, a frame 8009, a printed board 8010, a CPU 8011,and batteries 8012 a, 8012 b, 8012 c, and 8012 d are provided between anupper cover 8001 and a lower cover 8002.

The shapes and sizes of the upper cover 8001 and the lower cover 8002can be changed as appropriate in accordance with the sizes of the touchpanel 8004 and the display panel 8016.

The touch panel 8004 can be a resistive touch panel or a capacitivetouch panel and may be formed so as to overlap with the display panel8016. A counter substrate (sealing substrate) of the display panel 8016can have a touch panel function. A photosensor may be provided in eachpixel of the display panel 8016 so that an optical touch panel isobtained. The touch panel 8004 is connected to a printed board via theFPC 8003, and the printed board includes the battery 8012 a, a regulator8021, a receiving portion 8019, and the like. The receiving portion 8019includes an antenna for wireless charge, and electric power iswirelessly supplied from an external source to the battery 8012 a viathe regulator, whereby the battery 8012 a is charged. The touch panel8004 is driven mainly with the use of the battery 8012 a.

The display panel 8016 is an active matrix liquid crystal displaymodule, and is connected to a printed board via the FPC 8005. Theprinted board includes the battery 8012 b, a regulator 8018, a receivingportion 8020, and the like. The receiving portion 8020 includes anantenna for wireless charge, and electric power is wirelessly suppliedfrom an external source to the battery 8012 b via the regulator, wherebythe battery 8012 b is charged. The display panel 8016 displays an imageon a display region mainly with the use of the battery 8012 b.

The backlight unit 8007 includes a light source 8008 such as an LED.Furthermore, the backlight unit 8007 is connected to a printed board viaan FPC. The printed board includes the battery 8012 c, a regulator 8017,a receiving portion 8015, and the like.

Note that although a structure in which the light source 8008 isprovided over the backlight unit 8007 is illustrated in FIG. 9, oneembodiment of the present invention is not limited to this structure.For example, a structure in which the light source 8008 is provided atan end portion of the backlight unit 8007 and a light diffusion plate isfurther provided may be employed.

Note that the backlight unit 8007 may not necessarily be provided in thecase where the display panel 8016 is a display device using an organicEL element or a reflective liquid crystal display device. The backlightunit 8007 is provided in the case of a transmissive liquid crystaldisplay device or a transflective liquid crystal display device, forexample.

Note that as the display panel 8016, a display element, a display devicethat is a device including a display element, a light-emitting element,a light-emitting device that is a device including a light-emittingelement, or the like can employ various modes and can include variouselements.

The frame 8009 has a function of protecting the display panel 8016. Theframe 8009 can also function as a radiator plate. Furthermore, the frame8009 may incorporate an antenna of any of the receiving portions.

A control unit includes over the printed board 8010 the CPU 8011, thebattery 8012 d, a regulator 8013, a receiving portion 8014, and a signalprocessing circuit for outputting a video signal and a clock signal.

Since the electronic device 8000 is an information terminal, it has acommunication module as a communication function. That is, thecommunication module that realizes a wireless charging function isincorporated. Furthermore, the electronic device 8000 may incorporate acommunication module that realizes a near field wireless communicationfunction, which enables a phone call to be made. In that case, thecommunication module may also include a battery. The electronic device8000 can include another function such as a sensor (a sensor having afunction of measuring force, displacement, position, speed,acceleration, angular velocity, rotational frequency, distance, light,liquid, magnetism, temperature, chemical substance, sound, time,hardness, electric field, current, voltage, electric power, radiation,flow rate, humidity, gradient, oscillation, odor, or infrared rays), anda microphone.

One printed board is used for each of the functional circuits, andregulators and batteries are incorporated in order that an optimal poweroutput corresponding to each of the functional circuits is possible. Inaddition, the distance between the battery and the functional circuit isclose, and a lead wiring can be short, which can reduce powerconsumption.

Although an example in which one printed board is used for each of thefunctions and a plurality of printed boards are used in total is shownin FIG. 9, this embodiment is not limited thereto. All the functionalcircuits may be provided over one printed board, in which case aplurality of batteries are provided over the one printed board. Aplurality of functions may be provided over one printed board, and atthat time, a single battery instead of a plurality of batteries may beprovided. Each of the display panel 8016, the touch panel 8004, and thebacklight unit 8007 in FIG. 9 is electrically connected to the controlunit via a wiring cord or an FPC not shown in FIG. 9.

Furthermore, the electronic device 8000 may further be provided with aslot for insertion of a SIM card, a connector portion for connecting aUSB device such as a USB memory.

As described above, a battery is provided for each of the units (modulesor functions) to be used in the electronic device 8000, i.e., theelectronic device 8000 has a plurality of power supplies. The electronicdevice 8000 having a plurality of power supplies is provided with theoperation system that selectively drives only the function to be used,whereby power consumption can be reduced.

Furthermore, each of the batteries is provided with a communicationmodule that realizes a wireless charging function, and charging of theplurality of batteries at a time can be performed.

Although an example in which the electronic device 8000 has a box-likeshape is described in this embodiment, one embodiment of the inventionis not limited thereto. The electronic device may have a complex shape.In the case where an electronic device with a complex shape ismanufactured, a plurality of small-sized batteries are placed inpredetermined places as appropriate; whereby the degree of freedom indesign of the electronic device can be increased.

The structure described in this embodiment can be used in appropriatecombination with the structure described in any of the otherembodiments.

This application is based on Japanese Patent Application serial no.2014-017682 filed with Japan Patent Office on Jan. 31, 2014 and JapanesePatent Application serial no. 2014-017776 filed with Japan Patent Officeon Jan. 31, 2014, the entire contents of which are hereby incorporatedby reference.

What is claimed is:
 1. An electronic device comprising: a centralprocessing unit comprising a first battery, a first receiving portion,and a first transmitting portion, wherein the first receiving portionhas a function of wirelessly charging the first battery; a display unitcomprising a second battery, a second receiving portion, and a secondtransmitting portion, wherein the second receiving portion has afunction of wirelessly charging the second battery; a receiving unitcomprising a third battery, a third receiving portion, and a thirdtransmitting portion, wherein the third receiving portion comprises afunction of wirelessly charging the third battery; a transmitting unit;and a power supply management circuit having a function of charging atleast one of the first battery, the second battery, and the thirdbattery with electric power of at least one of the first battery, thesecond battery, and the third battery.
 2. The electronic deviceaccording to claim 1, wherein the first battery is electricallyconnected to the first receiving portion via a first regulator.
 3. Theelectronic device according to claim 1, wherein the second battery iselectrically connected to the second receiving portion via a secondregulator.
 4. The electronic device according to claim 1, wherein thethird battery is electrically connected to the third receiving portionvia a third regulator.
 5. An operation system comprising: a firstbattery; a second battery; a third battery; and a power supplymanagement circuit that manages the first battery, the second batteryand the third battery, wherein the power supply management circuitwirelessly supplies electric power from the first battery to the secondbattery or the third battery.
 6. The operation system according to claim5, wherein the first battery is electrically connected to a firstwireless receiving portion via a first regulator.
 7. The operationsystem according to claim 5, wherein the second battery is electricallyconnected to a second wireless receiving portion via a second regulator.8. The operation system according to claim 5, wherein the third batteryis electrically connected to a third wireless receiving portion via athird regulator.
 9. An electronic device comprising: a centralprocessing unit comprising a first battery and a first receivingportion, wherein the first receiving portion has a function ofwirelessly charging the first battery; a display unit comprising asecond battery and a second receiving portion, wherein the secondreceiving portion has a function of wirelessly charging the secondbattery; and a receiving unit comprising a third battery and a thirdreceiving portion, wherein the third receiving portion comprises afunction of wirelessly charging the third battery.
 10. The electronicdevice according to claim 9, wherein the first battery is electricallyconnected to the first receiving portion via a first regulator.
 11. Theelectronic device according to claim 9, wherein the second battery iselectrically connected to the second receiving portion via a secondregulator.
 12. The electronic device according to claim 9, wherein thethird battery is electrically connected to the third receiving portionvia a third regulator.
 13. An operation system comprising: a firstbattery; a second battery; a third battery; and a control unit thatmanages the first to third batteries, wherein the first battery, thesecond battery, and the third battery are wirelessly charged at a time.14. An electronic device comprising: a control module comprising acentral processing unit, a first battery, a first receiving portion, anda first transmitting portion; a display module comprising a displayportion, a second battery, a second receiving portion, and a secondtransmitting portion; a communication module comprising a communicationcircuit, a third battery, a third receiving portion, and a thirdtransmitting portion; and a power supply management circuit, wherein thefirst receiving portion has a function of wirelessly charging the firstbattery, the second receiving portion has a function of wirelesslycharging the second battery, and the third receiving portion has afunction of wirelessly charging the third battery, and wherein the powersupply management circuit has a function of charging at least one of thefirst battery, the second battery, and the third battery with electricpower of at least one of the first battery, the second battery, and thethird battery.
 15. The electronic device according to claim 14, whereinthe first battery is electrically connected to the first receivingportion via a first regulator.
 16. The electronic device according toclaim 14, wherein the second battery is electrically connected to thesecond receiving portion via a second regulator.
 17. The electronicdevice according to claim 14, wherein the third battery is electricallyconnected to the third receiving portion via a third regulator.
 18. Anoperation system comprising: a first battery; a second battery; a thirdbattery; and a power supply management circuit that manages the firstbattery, the second battery, and the third battery, wherein the powersupply management circuit is configured to wirelessly supply electricpower from the first battery to the second battery or the third battery.19. The operation system according to claim 18, wherein the firstbattery is electrically connected to a first receiving portion via afirst regulator.
 20. The operation system according to claim 18, whereinthe second battery is electrically connected to a second receivingportion via a second regulator.
 21. The operation system according toclaim 18, wherein the third battery is electrically connected to a thirdreceiving portion via a third regulator.